Hayley Atwell has admitted she screamed when she saw her older self in the mirror.

The 31-year-old actress spent hours in the make-up room for the ageing process as she reprised her role as Peggy Carter in Captain America: The Winter Soldier, and was taken aback by the final results.

"It was surreal. I fell asleep in the make-up chair and woke up and screamed, because I had the full make-up on without the wig," she said.

Hayley enjoyed shocking people with her new look.

"I had to have a restroom break so I drove around the Marvel studios as this bald, 92-year-old with this British accent," she recalled.

"People had no idea who I was or what I was doing there, and (I thought) I was about to be escorted off by security at any given moment. So it was surreal, but a lot of fun. It was great fun seeing the artistry that goes behind it, and the technique and the skill."

Hayley - who starred alongside Mathew Horne in a new adaptation of the play The Pride in London - was more than happy to return to her character, which she first played in the 2011 superhero film.

"It was great - more than anything, to be part of the Marvel family once again because I really love these guys. They're really genuinely nice to work for. Chris (Evans) is my buddy so to be able to come back was really lovely," she continued.

"It's a really great gig and it wasn't that much of my year - I went in, came out and went back to the London stage."

Anthony Mackie, Scarlett Johansson and Samuel L Jackson also star in Captain America: The Winter Soldier, which opens in cinemas on March 28.